You said the sixth line from the bottom is wrong. How is it wrong? This is the sixth line from the bottom:
y2−6y+(21×(−6))2=−9+(21×(−6))2 . How is it wrong?
Maybe I can explain. The first line which happens to be the fifth line from the bottom gave rise to the sixth line.
The original equation is
y2−6y+9=0To get the fifth line, I subtracted 9 from both sides of the equations and here comes the fifth line which is
y2−6y=−9To get the sixth line, I added the square of of half of the coefficient of y. The coefficient of y is -6. Half of it is
21×(−6)=−3 Square of -3 is
(−3)2=9Here comes the sixt line
y2−6y+(21×(−6))2=−9+(21×(−6))2I think what is wrong is the seventh line which is supposed to be
y2−6y+9=−9+9which I mistakenly wrote as
y2−6+9y=−9+9